Extrusion mill with vented feeder



1 J. T. KEEFE EXTRUSION MILL WITH VENTED FEEDEP June 29, 1965 2 Sheets-Shebt 1 Filed Sept. 1. 1961 INVENTOR. JAMES F KEEFE HIS ATTORNEYS June? 29;, 1 .965 .1 'r.. KEEFE 3,191,227

IZXLIRUSIQN MILL WITH VEN'IED FEEDER Filsd'a Sepia. 1,. 139,61 2' Sheets-Sheet 2- INVENTOR. JAMES 7'. KEEFE WMM H/S ATTORNEYS United States Patent 3,191,227 EXTRUSION MILL WITH VENTED FEEDER James T. Keefe, San tjarlos, Calif., assignor to California Pellet Mill Company, a corporation of alifornia Filed Sept. 1, 1961, Ser. No. 135,560 3 Claims. (Cl. 18-42) This invention relates to extrusion mills and more particularly to the type utilized in the pelleting of moldable material.

It is an improvement over the mill described and claimed in my co-pending application, Serial No. 77 3,440 filed November 12, 1958, now abandoned and refiled as continuation application, Serial No. 223,577 on September 10, 1962.

Essentially, that mill comprises a perforated hollow cylindrical die rotatable about a horizontal axis in a closed chamber and provided with rollers supported in an inner stationary frame to contact the inner face of the die and extrude a moldable material through the perforations thereof. To insure maximum and uniform feed to these rollers, particularly of bulky, light weight materials, there are provided preferably a plurality of spiral impeller blades which rotate with the die and have their edges in close proximity to a stationary conical ring in the feed inlet, so as to impel the feed with considerable force into the open end of the die chamber whereby it will be precompacted and in its precompacted condition, then acted upon by the rollers.

It was found that air entrained in the loose bulky material would become trapped in the die chamber under the influence of the impellers and, after suflicient pressure had developed, the entrapped air was apt to regurgitate, so to speak, back into the inlet feed chute and interfere with the normal and desired continuous flow.

This invention overcomes this disadvantage by a novel and eflicient arrangement of the feed mechanism carried by the rotating die and its relation to the die chamber and the conical ring.

The objects of this invention include:

(1) To provide a novel and improved arrangement of an extrusion mill in which the feed means for the die chamber are vented to the outlet of the die housing;

(2) To provide a novel and improved extrusion mill in which the material to be extruded is positively impelled into the die chamber and directed most efficiently to the extruding means with continuous separation of entrained air from the feed material and release of this air to the outlet of the unit, without interference with the feed;

(3) To provide a novel and improved feed arrangement which can be applied to existing extrusion mills with a minimum of modification thereof;

(4) To provide a novel and improved arrangement of an extrusion mill that will operate smoothly and continuously without air regurgitation due to air entrapment in the die chamber; and

(5) To provide a novel and improved feed mechanism for a pellet mill of the type in which pellets are formed by extrusion.

These and other objects and advantages will be further apparent from the following description, taken in conjunction with the attached drawings, which illustrates a preferred embodiment of the invention.

In the drawings:

FIGURE 1 is a longitudinal vertical sectional view of an extrusion mill embodying the invention.

FIGURE 2 is a transverse vertical sectional view on line 22 of the arrangement of FIGURE 1.

Referring to the drawings for details of the present invention, the same is disclosed in a mill of the character embodied in my aforementioned co-pending application, and insofar as the present invention is concerned, such 3,191,227 Patented June 29, 1965 mill involves a mill housing 1 having a front wall 3 adjacent which is rotatably supported a cylindrical die 5 with its longitudinal axis normal to the front wall of the housing, to provide a die chamber 7.

Located within the die chamber, are a pair of extrusion means such as rollers 9 for cooperating with the cylindrical die in the extrusion of moldable material through the die holes. These rollers are mounted within a horizontally disposed cage comprising a front end plate 11 and a rear end plate 13, the cage normally being stationary and serving to carry the spindles on which the rollers revolve.

Hinges l5 secure a movable door 17 to the mill housing. This door includes a substantially cylindrical side wall 18, and an end wall 19 provided with a feed chute 21 communicating with a feed opening 23 coaxial with the axis of die 5. The lower part of the door 17 is provided with one or more outlets 25 open to the atmosphere and selectively controlled as by a hinged fiap gate 27.

Mounted on the inner face of the door end wall 19 and concentric with feed opening 23 is a ring shaped member 29 having a circumferential mounting flange 31 which is desirably secured to the end wall by screws 33. The inner face 35 of ring 2) is conical and flares inwardly, and the outer face 37 is substantially cylindrical, for purposes to be described below. Thus, with the door 17 in its closed position and secured to mill housing 1, as by pins 39, ring 29 is concentric with die 5 and in spaced relation thereto.

In the space between the outer open end of die 5 and the ring 29, there is mounted a feeder blade assembly comprising, in this example, an outwardly diverging conical member 41 provided with an outside flange 42 at the smaller end for ailixing the member 41 to die 5 as by a circumferential chain clamp 43. An inwardly directed annular flange 45 is secured to the outer edge of member 41 and supports, preferably on its outer surface, a plurality of circumferentially spaced inwardly directed brackets 47, which terminate in proximity to the inner edge of the conical feed ring 29.

To the inner end of each bracket is mounted a blade 51 having one edge positioned closely adjacent and across the conical inner face 35 of ring member 29. These blades are helically inclined so that, as they rotate with the die 5, they will engage the incoming feed material and impel it with considerable velocity into the die chamber 7, where it will be precompacted prior to engagement by extrusion rollers 9.

T o facilitate travel of the feed material into the upper portion of die chamber 7, above rollers 9, to assure a more even distribution of the material to the rollers, a stationary scraper-deflector member 53 is supported on a post 55 on the front end plate 11 of the roller support cage. Desirably the scraper-deflector member 53 is shaped to conform closely to the inner surface of member 41 and extends a short distance into the die chamber 7, as shown.

In this connection, the outwardly flaring character of the member 41, makes accessible to the scraper-deflector member 53, an increased volume of feed material, thereby enhancing the effec-tiveness of the scraper-deflector in the performance of its function.

In the absence of provision to take care of the situation, air drawn into the die chamber with the material under the driving action of the impeller blades 51, tends to accumulate, and as the volume and pressure increase, such air is apt to break out of the die chamber and back up into the feed chute to temporarily interrupt the feeding process.

With this in mind, and to forestall such occurrences, the width of the inwardly directed flange 45 is such as to leave substantial space between it and the conical feed ring 29 to provide air vents 57, in part defined by the spiral blade brackets 47.

The presence of the flange 45, coupled with thevelocity with which the incoming material is driven into the die chamber, mitigates against escape of such material through the vents. This can be further assured by arranging the parts so that theconical ring 29 overhangs the flange 45. I

The foregoing; improvement, as. has already been pointed out above, improves materially the smoothness,

of operation of extrusion mills of this type, by effectively preventing the entrapment of air and the objectionable regurgitation of the same back into the inlet chute.

Although only asingle example has been illustrated and described, it is apparent that numerous changes could be made without departing from the spirit of the invention, and all such modifications that are within the scope of the appended .claims are intended to be embraced thereby. a

I claim: I

1. An extrusion mill having a perforated cylindrical die to provide a die chamber; means within said die chamher, for extruding material through said perforations; a housing enclosing said die and having a feed opening to said die chamber; a ring carried by said housing and having a conical surface flaring inwardly and substantially coaxial with said die chamber and'said feed opening; means for receiving material through said feed opening and precompactingthe same in said die chamber priorto extrusion through said die; said means including a plurality of spiral impeller blades circumferentially arranged with one edge of each in proximity to said conical surface and rotatable as a unit to positively impel feed material from said surface into said die chamber an-d precompact the same; and means forming at least one air vent passageway out of said mill from the region of precompaction and terminating in an exit lying outside the path of material being fed into said mill, whereby air entrained in said feed material is released from said region of precompaction in said die chamber without interruption of continuous flow of material into said mill. r

2. An extrusion mill having a perforated cylindrical die rotatably supported with its axis substantially horizontal to provide a die chamber; means within said die chamber for extruding material through said perforations; a housing enclosing said die and having a feed opening to said die chamber; a ring carried by said housing and having a conical surface flaring inwardly and substantially coaxial .with said die chamber and said feed opening; means for receiving material through said feed opening and precompacting the same prior to extrusion through said die; said means including a plurality of spiral impeller blades supported from and rotatable with said die and ci-rcumferentially arranged with one edge of each in proximity to said conical surface to positively impel feed material from said surface into said die chamber and precompact the same in said die chamberyand means forming at least one airi vent passageway out of said mill from the region of j precompaction in said die chamber and circumventingthe flow path of material intosaid mill, whereby air-entrained in said feed material is released from said region of precompaction without interruption of continuous flow of material into said mill.

3. An extrusion mill having a perforated cylindrical .die rotatably supported with its axis substantially horizontal to provide a die chamber; means-within said die chamber for extruding material through said perforations; a housing enclosing said die and having a feed opening to said die chamber; a ring carried by said housing and having a conical surface flaring inwardly and substantially coaxialtwith said die chamber and said feed opening; means for receiving material through said feed opening and precompacting the same prior to extrusion through said die; said means including an outwardly diverging conical member supported about the entrance to said die and a plurality of spiral impeller blades supported from and rotatable with said outwardly diverging conical member and circumferentially arranged with one edge of each in proximity to said' conical surface to positively impel feed material'from said surface into said die chamber and'precompact the same insaid die chamber; and means forming atleast one air vent passageway out of said mill from the region of precompaction in said die chamber and guarding against escape of material from said mill, whereby air entrained in said feed material is released from said region of precompaction without interruption of continuous flow of :material into said mill,- said means including an inwardly directed flange on 'the free' end of said outwardly diverging conical member and terminating in spaced relationship to said ring.

References Cited by the Examiner UNITED STATES PATENTS 2,240,660 5/41 Meakin 18--12 XR 2,764,951 10/56 Fisher 18--1-2 XR 2,798,444 7/57 Mcakin 18-12XR 2,887,718 5/59 Curran et a1 18-12 MICHAEL V. BRINDISI, Primary Examiner.- WILLIAM J. STEPHENSON, Examiner. 

1. AN EXTRUSION MILL HAVING A PERFORATED CYLINDRICAL DIE TO PROVIDE A DIE CHAMBER; MEANS WITHIN SAID DIE CHAMBER FOR EXTRUDING MATERIAL THROUGH SAID PERFORATIONS; A HOUSING ENCLOSING SAID DIE AND HAVING A FEED OPENING TO SAID DIE CHAMBER; A RING CARRIED BY SAID HOUSING AND HAVING A CONICAL SURFACE FLARING INWARDLY AND SUBSTASNTIALLY COAXIAL WITH SAID DIE CHAMBER AND SAID FEED OPENING; MEANS FOR RECEIVING MATERIAL THROUGH SAID FEED OPENING AND PRECOMPACTING THE SAME IN SAID DIE CHAMBER PRIOR TO EXTRUSION THROUGH SAID DIE; SAID MEANS INCLUDING A PLURALITY OF SPIRAL IMPELLER BLADES CIRCUMFERENTIALLY ARRANGED WITH ONE EDGE OF EACH IN PROXIMITY TO SAID CONICAL SURFACE AND ROTATABLE AS A UNIT TO POSITIVELY IMPEL FEED MA- 